1. Field of the Invention
The present invention relates to a fixing device that fixes an image to a recording medium, and an image forming apparatus including the fixing device.
2. Description of the Related Art
There is a known fixing device that is provided in an image forming apparatus, such as a copier or a printer, and that includes a heating area changing member capable of moving to change a heating area of a fixing member, such as a fixing roller or a fixing belt, heated by a heating unit.
The fixing device including the heating area changing member as described above may be provided with a position detection sensor that detects a position of the heating area changing member in order to improve the accuracy of a stop position of the heating area changing member in a moving destination.
For example, Japanese Patent Application Laid-open No. 2014-59332 proposes a device including two position detection sensors in order to control a movement stop position of a heating area changing member (shielding member). One of the two position detection sensors is used as an initial position detecting means for detecting the initial position of the heating area changing member, and the other is used as a position detecting means for detecting a position of the heating area changing member different from the initial position.
As described above, with use of the two position detection sensors, it is possible to improve the positional accuracy at the initial position and a moving destination different from the initial position of the heating area changing member. However, there is a demand for a reduction in the size and cost of the image forming apparatus, and therefore, there is a need to reduce the size and cost of the fixing device. To realize the reduction in the size and cost, it is desirable to control the position of the heating area changing member accurately with as small number of sensors as possible.